Modern wireless communications systems, and in particular cellular wireless communications systems, such as the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) system using Evolved Universal Terrestrial Radio Access (E-UTRA), may place a requirement on the spectrum emission requirements of radio equipment that depends on the territory in which the system is deployed and on the operating frequency band designation. For example, there may be more sensitive radio technology operating at neighbouring frequencies in some deployment situations and not in others, and so there may be a more or less stringent demands placed on the emissions in some deployment situations than in others. A user equipment may be capable of operating according to a number of different spectrum emission requirement capabilities, which may include out of band emission requirement capabilities, and a serving cell in a wireless communications network may signal a spectrum emission requirement value to a user equipment to instruct it to operate according to that value for a given frequency band designation. Typically, a user equipment may need to operate at a lower output power in order to achieve a more stringent spectrum emission requirement, which may limit the coverage and throughput of the system, so it is typically a disadvantage to apply a more stringent spectrum emission requirement value than is necessary in a given deployment.
The current handling of spectrum emission requirement in the LTE system, introduced from 3GPP LTE Release 8, supports the definition of multiple “NS” values (Network Signalled) for a band designation. The NS values correspond to a spectrum emission requirement value in addition to the minimum emission requirement specified for a user equipment. By broadcasting an NS value in a cell, an operator can force the user equipment to comply to more stringent spectrum emission requirements if, for example, a sensitive radio technology is neighbouring the operators deployment in a certain country. Besides spectrum emission requirements, the NS value may also affect A-MPR (Additional Maximum Power Reduction).
One requirement for conventional systems when defining an NS value and a corresponding spectrum emission requirement value for a band designation is that all user equipments supporting that band designation may have to support all NS values defined for this band. As a result, it is typically not possible with conventional systems to define additional NS values for existing band designations for which user equipments already exist in the field.
This may be a disadvantage, for example, if after a band designation is defined a new operator in a different country from that for which the band designation was originally defined may have the same spectrum available and also may want to start deploying LTE in that spectrum. However in this different country, there may be a sensitive technology neighbouring this spectrum and additional spectrum emission requirements may have to be defined if this band designation is to be used. So, in conventional systems the use of this spectrum using the same band designation may not be possible.